# MongoDB\Driver\ReadConcern::isDefault

(mongodb >=1.3.0)

MongoDB\Driver\ReadConcern::isDefault — Checks if this is the default read concern

### Beschreibung

final public MongoDB\Driver\ReadConcern::isDefault(): bool

Returns whether this is the default read concern (i.e. no options are specified). This method is primarily intended to be used in conjunction with MongoDB\Driver\Manager::getReadConcern() to determine whether the Manager has been constructed without any read concern options.

The driver will not include a default read concern in its read operations (e.g. MongoDB\Driver\Manager::executeQuery()) in order order to allow the server to apply its own default. Libraries that access the Manager's read concern to include it in their own read commands should use this method to ensure that default read concerns are left unset.

### Parameter-Liste

Diese Funktion besitzt keine Parameter.

### Rückgabewerte

Returns `true` if this is the default read concern and `false` otherwise.

### Fehler/Exceptions

- Wirft eine MongoDB\Driver\Exception\InvalidArgumentException, wenn beim Analysieren von Argumenten ein Fehler auftritt.

### Beispiele

Beispiel #1 MongoDB\Driver\ReadConcern::isDefault() example

`<?php
$rc = new MongoDB\Driver\ReadConcern(null);
var_dump($rc->isDefault());
$rc = new MongoDB\Driver\ReadConcern(MongoDB\Driver\ReadConcern::MAJORITY);
var_dump($rc->isDefault());
$manager = new MongoDB\Driver\Manager('mongodb://127.0.0.1/?readConcernLevel=majority');
$rc = $manager->getReadConcern();
var_dump($rc->isDefault());
$manager = new MongoDB\Driver\Manager('mongodb://127.0.0.1/');
$rc = $manager->getReadConcern();
var_dump($rc->isDefault());
?>`

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    bool(true)
    bool(false)
    bool(false)
    bool(true)

### Siehe auch

- MongoDB\Driver\Manager::getReadConcern() - Return the ReadConcern for the Manager
- » Read Concern reference

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